Regulation of oviposition in Anopheles gambiae s.s.: role of inter- and intra-specific signals.
Females of Anopheles gambiae Giles normally oviposit in a large number of fresh, small, sunlit, and spatially spread temporary pools. Such pools are associated with lower levels of predation compared to large, longer-lasting habitats. We compared oviposition levels on preferred (water collected from natural anopheline larval habitats) and non-preferred (distilled water) aqueous substrates by gravid females that contained different densities of conspecific eggs or early and late instar larvae. The presence of conspecific larvae, but not eggs, had a positive or negative effect on the ovipositional responses of gravid An. gambiae females, depending on the quality (preferred or non-preferred by the mosquito) of the oviposition water and the density of larvae. Presence of larvae, at all densities, in distilled water deterred oviposition. However, in natural anopheline pool water, a low density of larvae increased oviposition, whereas a higher density inhibited oviposition. Our results suggest that two signals produced by this mosquito may be involved in regulating oviposition: a volatile pheromone emitted by conspecific larvae, which augments the effect of a volatile signal emitted by preferred habitats, and a non-olfactory cue associated with high densities of larvae that deters oviposition.
Sumba
Leunita A
LA
International Centre of Insect Physiology and Ecology (ICIPE), P.O. Box 30772-00100, Nairobi, Kenya.
Ogbunugafor
C Brandon
CB
Deng
Arop L
AL
Hassanali
Ahmed
A
D000818:Animals; D000852:Anopheles / Q000254:growth & development / Q000502:physiology*; D004192:Discrimination, Psychological; D017753:Ecosystem; D005260:Female; D005618:Fresh Water; D007814:Larva / Q000254:growth & development; D010058:Oviposition; D014867:Water
D014867:Water